Poly(Sarcosine)-Based Nano-Objects with Multi-Protease Resistance by Aqueous Photoinitiated Polymerization-Induced Self-Assembly (Photo-PISA)

Abstract
Poly(sarcosine) (PSar) is a hydrophilic poly(peptoid) with numerous biologically relevant properties, making it an appealing candidate for the development of amphiphilic block copolymer nanostructures. In this work, the fabrication of poly(sarcosine)-based diblock copolymer nano-objects with various morphologies via aqueous reversible addition-fragmentation chain-transfer (RAFT)-mediated photoinitiated polymerization-induced self-assembly (photo-PISA) is reported. Poly(sarcosine) was first synthesized via ring-opening polymerization (ROP) of sarcosine N-carboxyanhydride, using high-vacuum techniques. A small molecule chain transfer agent (CTA) was then coupled to the active ω-amino chain end of the telechelic polymer for the synthesis of a poly(sarcosine)-based macro-CTA. Controlled chain-extensions of a commercially available water-miscible methacrylate monomer (2-hydroxypropyl methacrylate) were achieved via photo-PISA under mild reaction conditions, using PSar macro-CTA. Upon varying the degree of polymerization and concentration of the core-forming monomer, morphologies evolving from spherical micelles to worm-like micelles and vesicles were accessed, as determined by dynamic light scattering and transmission electron microscopy, resulting in the construction of a detailed phase diagram. The resistance of both colloidally stable empty vesicles and enzyme-loaded nanoreactors against degradation by a series of proteases was finally assessed. Overall, our findings underline the potential of poly(sarcosine) as an alternative corona-forming polymer to poly(ethylene glycol)-based analogues of PISA assemblies for use in various pharmaceutical and biomedical applications.

Citation
Varlas S, Georgiou PG, Bilalis P, Jones JR, Hadjichristidis N, et al. (2018) Poly(Sarcosine)-Based Nano-Objects with Multi-Protease Resistance by Aqueous Photoinitiated Polymerization-Induced Self-Assembly (Photo-PISA). Biomacromolecules. Available: http://dx.doi.org/10.1021/acs.biomac.8b01326.

Acknowledgements
This work was supported by the ERC (grant number 615142), EPSRC and King Abdullah University of Science and Technology (KAUST).

Publisher
American Chemical Society (ACS)

Journal
Biomacromolecules

DOI
10.1021/acs.biomac.8b01326

Additional Links
https://pubs.acs.org/doi/10.1021/acs.biomac.8b01326

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